Project description:MV130 is an inactivated polybacterial mucosal vaccine that confers protection to patients against recurrent respiratory infections, including those of viral etiology. We showed that MV130 induces long term heterologous protection against viral respiratory infections in mice. Moreover, intranasal administration of MV130 provided protection against systemic candidiasis in wild-type and Rag1-deficient mice lacking functional lymphocytes, indicative of innate immune-mediated protection. As trained immunity acts via modulation of hematopoietic stem and progenitor cells (Kaufmann et al., 2018; Mitroulis et al., 2018) we hypothesized that MV130 could confer systemic long-term protection through reprogramming of hematopoietic precursors. For that we measured the chromatin accessibility landscape in multipotent progenitors (MPPs) coming from mice treated with MV130 or its excipient using ATAC-seq.